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Discussion Starter · #1 ·
So I have this cafe racer I'm building, whole engines been treated so it ready to have a turbo put on, but before I start into that I wanna get it tuned right, and be able to tune it when it is turboed, so I'm going to invest in a wide band o2 sensor.. the bike is very basic and has very little electronics, so I guess I would have to run it closed loop? And just tap into the bike somewhere to find 5v to turn it on? Anyways, I wanna know which one you guys would say is better then the other for me, I think I'm leaning towards the aem right now.. also I'm putting the turbo right off the headers, like 6 inches down so it can use the thermal expansion of the hot exhaust, and then have like a 4 inch down pipe for the exhaust gasses out, so I have very little exhaust piping, I haven't put the turbo on yet so currently my pipes are like 30 inches long.. so where should I weld the bung on? Maybe it'll just have to read super lean at idle since it'll be really close to the atmosphere, cuz I was reading if they're to close to the hot headers sometimes they'll go whacko.. idk I'm a complete noob at this stuff looking for any advice, I put some different better carbs on the bike and it runs like shit so I really need to get it tuned up
 

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So I have this cafe racer I'm building, whole engines been treated so it ready to have a turbo put on, but before I start into that I wanna get it tuned right, and be able to tune it when it is turboed, so I'm going to invest in a wide band o2 sensor..

Sounds cool! What bike are you building this on?

the bike is very basic and has very little electronics, so I guess I would have to run it closed loop? And just tap into the bike somewhere to find 5v to turn it on?

Closed loop is talking about the control system for fuel injection. You seem to be doing this with carburetors, so it doesn't apply here. You power the gauge with 12v, not 5v. Read this.

Anyways, I wanna know which one you guys would say is better then the other for me, I think I'm leaning towards the aem right now..

AEM will work just fine.

also I'm putting the turbo right off the headers, like 6 inches down so it can use the thermal expansion of the hot exhaust, and then have like a 4 inch down pipe for the exhaust gasses out, so I have very little exhaust piping, I haven't put the turbo on yet so currently my pipes are like 30 inches long.. so where should I weld the bung on?

If you're just going to use the wideband for tuning when the turbo is installed, weld in a bung right before the flange to bolt the turbo on. More importantly, make sure the turbo is high enough that the oil in the turbo will drain back into the sump. How are you delivering oil to the turbo?

Maybe it'll just have to read super lean at idle since it'll be really close to the atmosphere, cuz I was reading if they're to close to the hot headers sometimes they'll go whacko.. idk I'm a complete noob at this stuff looking for any advice, I put some different better carbs on the bike and it runs like shit so I really need to get it tuned up

What bike did the carbs come from? When it comes to building a blow through turbo system there are some carb styles that do significantly better than others.

Added my two cents. There are a lot of things you still need to address here including
  • Upgraded fuel pump
  • Boost-compensated fuel pressure regulator
  • Carb float bowl pressurization
  • Oil delivery to the turbo

We all love turbo builds here, but there's a lot more that goes into one that one initially meets the eye.
 

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Discussion Starter · #3 ·
So the bike is an xs850 from Yamaha, its 3 cylinders and I just really like having that uniqueness, the carbs are off an xs750, the smaller brother, the 750's came with mikuni carbs and the 850's came with Hitachi carbs that are near impossible to tune, just cuz you can't get proper jets for them.. if I feel like dumping another $1000 then throttle bodies from a triumph speed triple bolt right up and I could go fi, but yes I wanna stick with blow through carbs for now.. this has almost been a year in the making(planning) there's a ton that goes into turboeing a bike, I'm actually thinking about keeping the turbos oil seperate from the bikes oil, have a small resiviour canister near the bottom of the bike with a pump, inline filter and a small oil cooler, I think it'd be easier then tapping into my oil pan somewhere, but I'm not set on that, I have picked out my oil and fuel pumps though, have the on my computer at home somewhere so that the amperage is still under what I can do.. think the fuel pump was around 20psi.. I think I'm only gonna run 5-7 pounds through this engine, 10 if I wanna get daring.. as of right now though I'm just collecting part so when I get outta school in a few weeks I can start building, right now I just wanna get the bike running good how it sits, I've gotten the jetting close enough so I don't have these explosive backfires(before the rebuild) but it still pops and is really down on power, I think a wide band would really speed up my tuning time, but I had the whole thing crygenically treated with new internals, so I'm thinking it should hold up to the power pretty well when it comes
 

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Discussion Starter · #4 ·
Oh and glad to know they run off 12v, I kept reading they need 5 volts so I was trying to figure out where I'd get that from.. so is it just really as easy putting 12v to the gauge, plugging in the o2 sensor and reading what it says? I think I'm gonna wanna get a throttle posistion sensor on there too just so can plug into my computer and see at what throttle openings I'm getting readings.. or maybe ill just eye ball it for now.. either way, wanna get the that aem! When it comes time to really dig into ill put a build thread up here.
 

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I have an innovate LM-1 wideband that has the ability to record afr vs. RPM and many other things if desired. You have to place the sensor in the downpipe of the turbo. I have mine about 6" down from the turbo. If you are looking to do things the right way then an LM-1 or the current LM-2 is necessary unless you have full access to a dyno. Turbos are great but are much more sensitive to tuning and susceptible to blowing up if things are not tuned correctly.
 
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